Standing on the 50-yard line that 2005 September night, the Michigan State teammates smiled, hugged and basked in the vitriol pouring out of the mouths of more than 80,000 fans inside Notre Dame Stadium.

“The crowd got the loudest it had in the entire game,” Thornhill laughed, describing the postgame atmosphere. “That is still the loudest boos I have ever heard in my entire life. I couldn’t hear anything.”

“It was probably one of the best feelings ever,” Smith added. “That was the loudest I ever heard that stadium. Maybe any stadium. They all started booing.”

The Irish faithful were upset.

After 10th-ranked Notre Dame erased a 21-point deficit in regulation, MSU tailback Jason Teague took an option pitch from quarterback Drew Stanton and dashed 19 yards down the sideline to cap a 44-41 overtime victory in South Bend.

What happened next, sent them into a rage.

As the Spartans spilled onto the field to celebrate their fifth straight road win in the series that night, Smith – or maybe it was his roommate, Thornhill – hatched a heat-of-the-moment plan.

Michigan State players from left, Jesse Miller (79), Tom Dance (26), Javon Ringer (39) and Travis Key (13) pose for a picture after the Spartans planted a Michigan State flag in the center of the field at Notre Dame Stadium following their 44-41 overtime victory on Sept. 17, 2005.(Photo: Joe Raymond/Associated Press)

They were going to “mark their territory” by planting a giant MSU flag at midfield.

“We saw one of the cheerleaders running with the flag,” said Smith, a senior defensive back for the Spartans. “I have to blame Kaleb. He said ‘let’s go grab that thing and go to the 50.’”

Thornhill, whose father Charlie was a legend at MSU in the '60s and whose older brother, Josh, played linebacker for the Spartans from 1998 to 2001, remembers it differently.

“Smitty said, 'Do you want to take the flag to the middle of the field?’ I said, ‘Why not?’

The duo slowly made their way from the end zone to midfield, each with a hand wrapped around the white flag pole. When they got to their intended target, they violently spiked the flag into the turf below, surrounded by more than a dozen teammates.

“It was a culmination of all the emotion and the work we put in,” said Thornhill, who is now the director of player development for the Miami Dolphins. “It was impulsive. That’s what’s special about the game of football. We were in the moment, and we slammed that flag in the middle of the field.”

Smith added that comments from Notre Dame’s first-year head coach Charlie Weis also led to the postgame shenanigans.

Speaking at a pep rally in South Bend the night prior, Weis, who was set to make his home debut, fired up the student body, saying “The last thing I am going to say to you is, I’m going to be looking for you about 5:40 after we are 3-0.”

Notre Dame coach Charlie Weis motions to a player during the fourth quarter against Michigan State, Saturday, Sept. 17, 2005, in South Bend, Ind. Notre Dame lost 44-41 in overtime.(Photo: John Harrell/Associated Press)

It was the Spartans who would leave South Bend unbeaten.

“Weis guaranteeing a victory before the game,” Smith said about the motivation behind the flag planting. “Honestly, we didn’t think about it, we were caught up in the emotion. With all the trash talk leading up to the game, and (Notre Dame players) would talk trash, it all culminated. They thought of us as little brother and that Michigan was the real school in the state.”

Thornhill, who said he played more than 100 plays in the game and finished with 11 tackles, didn’t issue any apologies, nor will he. He said he heard Weis’ words. The former linebacker said he gets goosebumps just thinking back to that night.

“To hear him make those comments made us mad,” he said. “A statement before a game never won anything. That was the ultimate disrespect. When you do that, and make a statement like that, (planting the flag) was just icing on the cake.”

Thornhill still has a photo of himself and his teammates standing around the flag and holding the megaphone, the traveling trophy between the two schools, in a frame on his desk. He said he likes to post it to his social media accounts every year when this game rolls around.

“That passion and purpose has carried me through,” Thornhill said. “That game propelled me into life after football. It’s built in rivalries like that.”

Thornhill, who graduated from Lansing Eastern, said one word comes to mind when he thinks about that 2005 night – “Epic.”

As far as this season’s rendition of the rivalry goes, Thornhill said he isn’t in the business of making predictions. This matchup is the last one in the series until 2026, with Notre Dame shedding some of its non-conference opponents for a more pro-ACC schedule.

Running back Jason Teague of the Michigan State Spartans rushes for a 19-yard touchdown to win the game in overtime against the Notre Dame Fighting Irish on September 17, 2005, at Notre Dame Stadium in South Bend, Indiana. Michigan State defeated Notre Dame 44-41 in OT.(Photo: Elsa/Getty Images)

Smith, who lives in New Jersey, wouldn’t predict the score, but added that he likes the Spartans chances under the lights Saturday night in East Lansing. He joked that he would like a “reenactment” of the 2005 game, but said it’s not near as fun spiking a flag into your own field.

“A blowout would be even better,” Smith laughed.

Contact Cody Tucker at (517) 377-1070 or cjtucker@lsj.com and follow him on Twitter @CodyTucker_LSJ.